Base station apparatus, terminal apparatus, communication method, and integrated circuit

ABSTRACT

A terminal apparatus for communicating with a base station apparatus includes a transmission unit configured to transmit Phase-tracking reference signals (PTRS), and an higher layer processing unit configured to configure information for indicating a time density and/or a frequency density of the PTRS. A PTRS pattern is configured such that the time density of the PTRS is higher for a larger Modulation and Coding Scheme (MCS) scheduled for the terminal apparatus, and the frequency density of the PTRS is based on the number of resource blocks scheduled for the terminal apparatus.

TECHNICAL FIELD

The present invention relates to a base station apparatus, a terminalapparatus, a communication method, and an integrated circuit.

This application claims priority based on JP 2017-017375 filed on Feb.2, 2017, the contents of which are incorporated herein by reference.

BACKGROUND ART

Currently, the Third Generation Partnership Project (3GPP) is conductinga technical study and standardization of Long Term Evolution(LTE)-Advanced Pro and New Radio technology (NR) as a radio accessmethod and a radio network technology for the 5th generation cellularsystem (NPL 1).

In the 5th generation cellular system, three technologies are requiredfor the expected service scenario, that is, enhanced Mobile BroadBand(eMBB) to realize a high-speed and high-capacity transmission,Ultra-Reliable and Low Latency Communication (URLLC) to realize a lowdelay and highly reliable communication, and massive Machine TypeCommunication (mMTC), such as Internet of Things (IoT), that allows alarge number of machine type devices to be connected.

In NR, reference signals for tracking phase noise generated by anoscillator have been studied for communication at high frequencies. (NPL2).

CITATION LIST Non Patent Literature

NPL 1: RP-161214, NTT DOCOMO, “Revision of SI: Study on New Radio AccessTechnology”, June 2016

NPL 2: R1-1701435, Mitsubishi Electric, CATT, InterDigital, Intel,Qualcomm, “WF on PT-RS for DFTs OFDM”, January 2017

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a terminal apparatus, abase station apparatus, a communication method, and an integratedcircuit for efficiently communicating in the above-mentioned radiocommunication systems.

Solution to Problem

(1) To accomplish the object described above, aspects of the presentinvention are contrived to provide the following measures. A terminalapparatus according to one aspect of the present invention is a terminalapparatus for communicating with a base station apparatus, the terminalapparatus including: a transmission unit configured to transmitPhase-tracking reference signals (PTRS), and an higher layer processingunit configured to configure information for indicating a time densityand/or a frequency density of the PTRS. A PTRS pattern is configuredsuch that the time density of the PTRS is higher for a larger Modulationand Coding Scheme (MCS) scheduled for the terminal apparatus, and thefrequency density of the PTRS is based on the number of resource blocksscheduled for the terminal apparatus.

(2) In the terminal apparatus according to one aspect of the presentinvention, the PTRS are not generated in accordance with a rule based onthe MCS and/or the number of resource blocks scheduled for the terminalapparatus.

(3) In the terminal apparatus according to one aspect of the presentinvention, the PTRS are selected from a plurality of the PTRS patternsdefined in advance.

(4) In the terminal apparatus according to one aspect of the presentinvention, information for indicating the time density and/or thefrequency density of the PTRS includes information for indicating thePTRS pattern.

(5) In the terminal apparatus according to one aspect of the presentinvention, the transmission unit transmits capability information forindicating whether a capability of transmitting PTRS signals issupported.

(6) A base station apparatus according to one aspect of the presentinvention is a base station apparatus for communicating with a terminalapparatus, the base station apparatus including: a reception unitconfigured to receive Phase-tracking reference signals (PTRS); and ahigher layer processing unit configured to configure information forindicating a time density and a frequency density of the PTRS, in theterminal apparatus. The terminal apparatus uses the time density of thePTRS which is higher for a larger Modulation and Coding Scheme (MCS)scheduled for the terminal apparatus is higher, and the frequencydensity of the PTRS is based on the number of scheduled resource blocksfor the terminal apparatus.

Advantageous Effects of Invention

According to one aspect of the present invention, a base stationapparatus and a terminal apparatus efficiently communicate with eachother.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a concept of a radio communicationsystem according to the present embodiment.

FIG. 2 is a diagram illustrating an example of a schematic configurationof an uplink slot according to the present embodiment.

FIG. 3 is a diagram illustrating a relationship in a time domain of asubframe, a slot, and a mini-slot.

FIG. 4 is a diagram illustrating an example of a slot or a subframe.

FIG. 5 is a diagram illustrating an example of beam forming.

FIGS. 6A to 6I are diagrams, each illustrating a first configurationexample of PTRS mapped to a single resource element.

FIG. 7A is a diagram illustrating a second configuration example of PTRSmapped to a single resource element.

FIG. 8 is a schematic block diagram illustrating a configuration of aterminal apparatus 1 according to the present embodiment.

FIG. 9 is a schematic block diagram illustrating a configuration of abase station apparatus 3 according to the present embodiment.

FIG. 10 is a diagram illustrating an overview of a flow of a firstprocess between the base station apparatus 3 and the terminal apparatus1 according to the present embodiment.

FIG. 11 is a diagram illustrating an overview of a flow of a secondprocess between the base station apparatus 3 and the terminal apparatus1 according to the present embodiment.

FIG. 12 is a diagram illustrating an overview of a flow of a thirdprocess between the base station apparatus 3 and the terminal apparatus1 according to the present embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below.

FIG. 1 is a conceptual diagram of a radio communication system accordingto the present embodiment. In FIG. 1, a radio communication systemincludes terminal apparatuses 1A to 1C and a base station apparatus 3.Hereinafter, the terminal apparatuses 1A to 1C are each also referred toas a terminal apparatus 1.

The terminal apparatus 1 is also called a user terminal, a mobilestation device, a communication terminal, a mobile device, a terminal,User Equipment (UE), and a Mobile Station (MS). The base stationapparatus 3 is also called a radio base station apparatus, a basestation, a radio base station, a fixed station, a NodeB (NB), an evolvedNodeB (eNB), a Base Transceiver Station (BTS), a Base Station (BS), anNR NodeB (NR NB), an NNB, a Transmission and Reception Point (TRP), anda gNB.

In FIG. 1, Orthogonal Frequency Division Multiplexing (OFDM) includingCyclic Prefix (CP), Single Carrier Frequency Division Multiplexing(SC-FDM), Discrete Fourier Transform Spread OFDM (DFT-S-OFDM), andMulti-Carrier Code Division Multiplexing (MC-CDM) may be used for radiocommunication between the terminal apparatus 1 and the base stationapparatus 3.

In FIG. 1, in the radio communication between the terminal apparatus 1and the base station apparatus 3, Universal-Filtered Multi-Carrier(UFMC), Filtered OFDM (F-OFDM), OFDM in which a window is multiplied(Windowed OFDM), and Filter-Bank Multi-Carrier (FBMC) may be used.

Note that the present embodiment will be described by using OFDM symbolwith the assumption that a transmission scheme is OFDM, and use of anyother transmission scheme is also included in an aspect of the presentinvention.

In FIG. 1, the aforementioned transmission scheme that uses no CP oruses zero padding instead of the CP may be used for the radiocommunication between the terminal apparatus 1 and the base stationapparatus 3. Further, the CP and the zero padding may be added bothforward and backward.

In FIG. 1, Orthogonal Frequency Division Multiplexing (OFDM) includingCyclic Prefix (CP), Single Carrier Frequency Division Multiplexing(SC-FDM), Discrete Fourier Transform Spread OFDM (DFT-S-OFDM), andMulti-Carrier Code Division Multiplexing (MC-CDM) may be used for radiocommunication between the terminal apparatus 1 and the base stationapparatus 3.

In FIG. 1, the following physical channels are used for radiocommunication between the terminal apparatus 1 and the base stationapparatus 3.

-   -   Physical Broadcast CHannel (PBCH)    -   Physical Control CHannel (PCCH)    -   Physical Shared CHannel (PSCH)

The PBCH is used to broadcast an important information block (MasterInformation Block: MIB, Essential Information Block: EIB, BroadcastChannel: BCH) including important system information required by theterminal apparatus 1.

In a case of uplink radio communication (radio communication from theterminal apparatus 1 to the base station apparatus 3), the PCCH is usedto transmit Uplink Control Information (UCI). Here, the uplink controlinformation may include Channel State Information (CSI) used to indicatea downlink channel state. The uplink control information may includeScheduling Request (SR) used to request an UL-SCH resource. The uplinkcontrol information may include Hybrid Automatic Repeat reQuestACKnowledgment (HARQ-ACK). The HARQ-ACK may indicate HARQ-ACK fordownlink data (Transport block, Medium Access Control Protocol Data Unit(MAC PDU), Downlink-Shared Channel (DL-SCH)).

Furthermore, in a case of downlink radio communication (radiocommunication from the base station apparatus 3 to the terminalapparatus 1), the PCCH is used to transmit Downlink Control Information(DCI). Here, one or more DCIs (which may be referred to as DCI formats)are defined for transmission of the Downlink Control Information. Thatis, a field for the Downlink Control Information is defined as the DCI,and is mapped to information bits.

For example, DCI including information for indicating whether a signalincluded in the scheduled PSCH is a downlink radio communication oruplink radio communication may be defined.

For example, DCI including information for indicating a downlinktransmission period included in the scheduled PSCH may be defined.

For example, DCI including information for indicating an uplinktransmission period included in the scheduled PSCH may be defined.

For example, DCI including information for indicating a timing fortransmitting HARQ-ACK for the scheduled PSCH (for example, the number ofsymbols from the last symbol included in the PSCH to the HARQ-ACKtransmission) may be defined.

For example, DCI including information for indicating a downlinktransmission period, a gap, and an uplink transmission period that areincluded in the scheduled PSCH may be defined.

For example, DCI to be used for scheduling a PSCH for downlink radiocommunication in one cell (transmission of one downlink transport block)may be defined.

For example, DCI to be used for scheduling a PSCH for uplink radiocommunication in one cell (transmission of one uplink transport block)may be defined.

Here, information on scheduling of the PSCH is included in the DCI in acase that an uplink or a downlink is included in the PSCH. Here, the DCIfor the downlink is also referred to as downlink grant or downlinkassignment. Here, the DCI for the uplink is also referred to as uplinkgrant or Uplink assignment.

The PSCH is used to transmit uplink data (Uplink Shared CHannel: UL-SCH)or downlink data (Downlink Shared CHannel: DL-SCH) from Medium AccessControl (MAC). In a case of the downlink, the PSCH is also used totransmit System Information (SI) and Random Access Response (RAR). In acase of the uplink, the PSCH may be used to transmit HARQ-ACK and/orCSI, together with the uplink data. Furthermore, the PSCH may be used totransmit CSI only or HARQ-ACK and CSI only. That is, the PSCH may beused to transmit UCI only.

Here, the base station apparatus 3 and the terminal apparatus 1 exchange(transmit and/or receive) signals with each other in their respectivehigher layers. For example, the base station apparatus 3 and theterminal apparatus 1 may transmit and receive radio resource control(RRC) signaling (also referred to as RRC message or RRC information) inthe RRC layer, respectively. The base station apparatus 3 and theterminal apparatus 1 may transmit and receive a Medium Access Control(MAC) control element in a MAC layer, respectively. Here, the RRCsignaling and/or the MAC control element is also referred to as higherlayer signaling.

The PSCH may be used to transmit the RRC signaling and the MAC controlelement. Here, the RRC signaling transmitted from the base stationapparatus 3 may be signaling common to multiple terminal apparatuses 1in a cell. The RRC signaling transmitted from the base station apparatus3 may be signaling dedicated to a certain terminal apparatus 1 (alsoreferred to as dedicated signaling). In other words, terminalapparatus-specific (UE-specific) information may be transmitted throughsignaling dedicated to the certain terminal apparatus 1. The PSCH may beused to transmit UE Capability in the uplink.

Although the names PCCH and PSCH are consistently used for both thedownlink and uplink, different channels may be defined for the downlinkand uplink.

For example, the downlink shared channel may be referred to as aPhysical Downlink Shared CHannel (PDSCH). The uplink shared channel maybe referred to as a Physical Uplink Shared CHannel (PUSCH). The downlinkcontrol channel may be referred to as a Physical Downlink ControlCHannel (PDCCH). The uplink control channel may be referred to as aPhysical Uplink Control CHannel (PUCCH).

In FIG. 1, the following downlink physical signals are used for downlinkradio communication. Here, the downlink physical signals are not used totransmit the information output from the higher layers but is used bythe physical layer.

-   -   Synchronization Signal (SS)    -   Reference Signal (RS)

The synchronization signal may include a Primary Synchronization Signal(PSS) and a Second Synchronization Signal (SSS). Cell IDs may bedetected using the PSS and the SSS.

The synchronization signal is used for the terminal apparatus 1 to takesynchronization in the frequency domain and the time domain in thedownlink. Furthermore, the synchronization signal may be used for theterminal apparatus 1 to perform a selection regarding the precoding bythe base station apparatus 3 or a selection regarding the precoding orbeam in the beamforming.

The reference signal is used for the terminal apparatus 1 to performchannel compensation on a physical channel. The reference signal mayalso be used in order for the terminal apparatus 1 to obtain thedownlink CSI. In addition, the reference signal may be used for a radioparameter, a numerology such as a subcarrier spacing, and finesynchronization that allows FFT window synchronization, or the like tobe performed.

According to the present embodiment, one or more of the followingdownlink reference signals are used.

-   -   Demodulation reference signal (DMRS)    -   Channel state information reference signal (CSI-RS)    -   Phase tracking reference signal (PTRS)    -   Mobility reference signal (MRS)

The DMRS is used to demodulate a modulated signal. Note that the DMRSmay have two defined types of reference signals for demodulating thePBCH and for demodulating the PSCH, and both of them may be referred toas DMRS. The CSI-RS is used to measure Channel State Information (CSI)and perform beam management. The PTRS is used to track phase shifts dueto movement of terminals and the like. The MRS may be used to measurereception quality from a plurality of base station apparatuses forhandovers. A reference signal for compensating for phase noise may alsobe defined as the reference signal.

The downlink physical channels and/or the downlink physical signals arecollectively referred to as a downlink signal. The uplink physicalchannels and/or the uplink physical signals are collectively referred toas an uplink signal. The downlink physical channels and/or the uplinkphysical channels are collectively referred to as a physical channel.The downlink physical signals and/or the uplink physical signals arecollectively referred to as a physical signal.

The BCH, the UL-SCH, and the DL-SCH are transport channels. A channelused in a Medium Access Control (MAC) layer is referred to as atransport channel. A unit of the transport channel used in the MAC layeris also referred to as a Transport Block (TB) and/or a MAC Protocol DataUnit (PDU). A Hybrid Automatic Repeat reQuest (HARM) is controlled foreach transport block in the MAC layer. The transport block is a unit ofdata that the MAC layer delivers to the physical layer. In the physicallayer, the transport block is mapped to a codeword, and codingprocessing is performed for each codeword.

The reference signal may also be used for Radio Resource Measurement(RRM). The reference signal may also be used for beam management.

The beam management may be a procedure performed by the base stationapparatus 3 and/or the terminal apparatus 1 for acquiring beam gains bymatching directionality of an analog and/or digital beam in atransmission device (the base station apparatus 3 for downlink and theterminal apparatus 1 for uplink) and directionality of an analog and/ordigital beam in a reception device (the terminal apparatus 1 fordownlink and the base station apparatus 3 for uplink).

Note that the beam management may include the following procedures.

-   -   Beam selection    -   Beam refinement    -   Beam recovery

For example, the beam selection may be a procedure for selecting a beamin communications between the base station apparatus 3 and the terminalapparatus 1. Furthermore, the beam refinement may be a procedure forselecting a beam with a higher gain or changing beams between theoptimal base station apparatus 3 and the terminal apparatus 1 due to themovement of the terminal apparatus 1. The beam recovery may be aprocedure for reselecting a beam in a case that the quality of thecommunication link decreases due to blockage, caused by a blocking body,passage of a person, or the like, in communications between the basestation apparatus 3 and the terminal apparatus 1.

For example, the CSI-RS may be used by the terminal apparatus 1 inselecting a transmission beam from the base station apparatus 3, or aQuasi Co-Location (QCL) assumption may be used.

In a case that Long Term Property of a channel on which a symbol on anantenna port is carried can be estimated from a channel on which asymbol on another antenna port is carried, the two antenna ports aresaid to be quasi co-located (in a QCL state). The Long Term Propertyincludes one or a plurality of delay spread, Doppler spread, Dopplershift, average gain, and average delay. For example, in a case that anantenna port 1 and an antenna port 2 are in the QCL state in terms ofaverage delay, the reception timing of the antenna port 2 may beinferred from the reception timing of the antenna port 1.

The QCL may also be expanded to beam management. Thus, spatiallyexpanded QCL may be newly defined. Examples of the Long Term Property ofa channel in spatial QCL assumption may include an Angle of Arrival(AoA) or a Zenith angle of Arrival (ZoA), an Angle Spread (an AngleSpread of Arrival (ASA) or a Zenith angle Spread of Arrival (ZSA) forexample), an Angle of Departure (AoD or ZoD for example) and their AngleSpreads (for example, Angle Spread of Departure (ASD), Zenith angleSpread of Departure (ZSS)), and Spatial Correlation in a wireless linkor a channel.

Thus, an operation of the base station apparatus 3 and the terminalapparatus 1 equivalent to the beam management based on spatial QCLassumption and radio resource (time and/or frequency) may be defined asthe beam management.

The subframe will now be described. The subframe in the embodiment mayalso be referred to as a resource unit, a radio frame, a time period, ora time interval.

FIG. 2 is a diagram illustrating a schematic configuration of an uplinkslot according to a first embodiment of the present invention. Each ofthe radio frames is 10 ms in length. Each of the radio frames isconstituted of 10 subframes and X slots. In other words, each subframehas a length of 1 ms. The time length of each of the slots is defined bysubcarrier spacing. For example, in a case of Normal Cyclic Prefix (NCP)with the subcarrier spacing of OFDM symbols being 15 kHz, X is 7 or 14respectively corresponding to 0.5 ms or 1 ms. In addition, in a casethat the subcarrier spacing is 60 kHz, X is 7 or 14 respectivelycorresponding to 0.125 ms or 0.25 ms. FIG. 2 illustrates an example of acase that X is 7. Note that the case can be similarly extended to a casethat X is 14. The uplink slot may be defined similarly, and the downlinkslot and the uplink slot may be defined separately from one another.

The signal or the physical channel transmitted in each of the slots maybe expressed by a resource grid. The resource grid is defined by aplurality of subcarriers and a plurality of OFDM symbols. The number ofsubcarriers constituting one slot depends on a bandwidth of a cell ineach of the downlink and the uplink. Each element within the resourcegrid is referred to as a resource element. The resource element may beidentified by a subcarrier number and an OFDM symbol number.

A resource block is used to express mapping of a certain physicaldownlink channel (such as the PDSCH) or a certain physical uplinkchannel (such as the PUSCH) to resource elements. For the resourceblock, a virtual resource block and a physical resource block aredefined. A certain physical uplink channel is first mapped to a virtualresource block. Thereafter, the virtual resource block is mapped to thephysical resource block. In the case of NCP with the number of OFDMsymbols being X=7, one physical resource block is defined by sevenconsecutive OFDM symbols in the time domain and by 12 consecutivesubcarriers in the frequency domain. Hence, one physical resource blockincludes (7×12) resource elements. In a case of Extended CP (ECP), onephysical resource block is defined by six consecutive OFDM symbols inthe time domain and by 12 consecutive subcarriers in the frequencydomain. Hence, one physical resource block includes (6×12) resourceelements. Furthermore, one physical resource block corresponds to oneslot in the time domain and corresponds to 180 kHz in the frequencydomain in a case that the subcarrier spacing is 15 kHz (720 kHz in acase that the subcarrier spacing is 60 kHz). Physical resource blocksare numbered from 0 in the frequency domain.

Next, a subframe, a slot, and a minislot will be described. FIG. 3 is adiagram illustrating a relationship among a subframe, a slot, and amini-slot in a time domain. As illustrated in the figure, three types oftime units are defined. The subframe is 1 ms regardless of thesubcarrier spacing, whereas the slot includes 7 or 14 OFDM symbols andhas a slot length depending on the subcarrier spacing. Specifically, ina case that the subcarrier spacing is 15 kHz, a single subframe includes14 OFDM symbols. Thus, in a case that the subcarrier spacing is Δf(kHz), the slot length may be defined as 0.5/(Δf/15) ms in a case that asingle slot includes seven OFDM symbols. This Δf may be defined bysubcarrier spacing (kHz). The slot length may be defined as 1/(Δf/15) msin a case that a single slot includes seven OFDM symbols. This Δf may bedefined by subcarrier spacing (kHz). Furthermore, the slot length may bedefined as X/14/(Δf/15) ms, where X is the number of OFDM symbols in aslot.

The mini-slot (which may be referred to as a sub-slot) is a time unitincluding OFDM symbols that are less than the number of OFDM symbolsincluded in a slot. The figure illustrates an example of a case that themini-slot includes 2 OFDM symbols. The OFDM symbols in the mini-slot andthe OFDM symbols in the slot may match in timing. Note that a slot ormini-slot may be the minimum scheduling unit. Also,

FIG. 4 is a diagram illustrating an example of a slot or a subframe.Here, an example of a case is illustrated in which the slot length is0.5 ms with the subcarrier spacing being 15 kHz. In the figure, Drepresents the downlink, and U represents the uplink. As illustrated inthe figure, during a certain time duration (for example, the minimumtime duration to be allocated to an UE in the system), the subframe mayinclude one or more of the followings:

-   -   a downlink part (duration);    -   the gap    -   an uplink part (duration).

Part (a) of FIG. 4 illustrates an example in which the entire subframeis used for downlink transmission during a certain time duration (forexample, a minimum time resource unit that can be allocated to a UE,which may also be referred to as a time unit. Furthermore, a combinationof a plurality of minimum time resource units may be referred to as atime unit). Part (b) of FIG. 4 illustrates an example in which an uplinkis scheduled via a PCCH for example by using the first time resource,and an uplink signal is transmitted after a gap for a processing delayof the PCCH, a time for switching from a downlink to an uplink, andgeneration of a transmit signal. Part (c) of FIG. 4 illustrates anexample in which a downlink PCCH and/or downlink PSCH are transmitted byusing the first time resource, and a PSCH or PCCH is transmitted after agap for a processing delay, a time for switching from a downlink to anuplink, and generation of a transmit signal. Here, for example, theuplink signal may be used to transmit the HARQ-ACK and/or CSI, namely,the UCI. Part (d) of FIG. 4 illustrates an example in which a downlinkPCCH and/or a downlink PSCH are transmitted by using the first timeresource, and a PSCH or PCCH is transmitted after a gap for a processingdelay, a time for switching from a downlink to an uplink, and generationof a transmit signal. Here, for example, the uplink signal may be usedto transmit the uplink data, namely, the UL-SCH. Part (e) of FIG. 4illustrates an example in which the entire subframe is used for uplinktransmission (uplink PSCH or PCCH).

The above-described downlink part and uplink part may include multipleOFDM symbols as is the case with LTE.

FIG. 5 illustrates an example of the beamforming. A plurality of antennaelements are connected to a single transmission unit (Transceiver unit(TXRU)) 10, and a beam can be directed to a desired direction for atransmission signal with the antenna elements 12 performing transmissionwith a phase shifter 11 of each of the antenna elements performing phasecontrol. Typically, the TXRU may be defined as an antenna port, and onlythe antenna port may be defined in the terminal apparatus 1. Thedirectivity in a desired direction can be obtained by controlling thephase shifter 11, whereby the base station apparatus 3 can communicatewith the terminal apparatus 1 using a beam with a high gain.

FIGS. 6A to 6I are diagrams, each illustrating a first configurationexample of PTRS mapped to a first resource element. In FIGS. 6A to 6I, ahatched section represents a resource element to which PTRS is mapped,and other sections represent resource elements to which data is mapped.In FIGS. 6A to 6I, FIGS. 6A to 6I are respectively defined as Patterns 1to 9. Patterns 1 to 3 are examples in which PTRS are continuously mappedin the time direction. Patterns 4 to 6 are examples in which PTRS aremapped at an interval with one symbol in the time direction, andPatterns 7 through 9 are examples of mapping at an interval with twosymbols in the time direction. Note that the PTRS are not limited toFIGS. 6A to 6I, and may be mapped at an interval with more than twosymbols in the time direction. The interval in the frequency directionand the subcarrier positions are also not limited to those in FIGS. 6Ato 6I. One or a plurality of the patterns illustrated in FIGS. 6A to 6Imay be defined for the PTRS. Note that the PTRS mapping pattern may beconfigured in advance as illustrated in FIGS. 6A to 6I, and PTRS may begenerated based on the pattern number. Alternatively, PTRS may begenerated by specifying a position where the PTRS is mapped.

FIG. 7A is a diagram illustrating a second configuration example of PTRSmapped to a single resource element. In FIG. 7A, a hatched sectionrepresents a resource element onto which PTRS is mapped, and anothersection represents a resource element to which data is mapped. FIG. 7Ais defined as Pattern 10. Pattern 10 of FIG. 7A is an example where PTRSis mapped at an interval with one symbol in the time direction in thesubcarriers whose numbers are identical to those of Pattern 5 in FIGS.6A to 6I, but the mapping positions of the PTRS on the fourth subcarrierfrom the top is different from those of Pattern 5 in FIGS. 6A to 6I.

Here, the terminal apparatus 1 may not have a PUSCH signal mapped to aresource element to which PTRS has been mapped. In other words, in thecase that the PUSCH signal is not mapped, a rate match may be applied inwhich the resource element with the PTRS mapped does not serve as aresource element to which the PUSCH signal can be mapped. The PUSCHsignal mapped to the resource element to which PTRS is mapped may beoverwritten with PTRS. In this case, the base station apparatus 3 mayperform demodulation processing assuming that data is mapped to theresource element with PTRS mapped.

Different PTRS may be generated differently depending on a frequencyband. In a low frequency band that is less susceptible to phase rotationa smaller number of resource elements to which PTRS are mapped may beconfigured. In a high frequency band susceptible to phase rotation alarger number of resource elements to which PTRS are mapped may beconfigured. PTRS may be configured for each frequency band as in anexample where Pattern 7 is configured in a case that the frequency bandis 4 GHz, and Pattern 2 is configured in a case that the frequency bandis 40 GHz. PTRS may be configured for each frequency band as in anexample where Pattern 2 is configured in the case that the frequencyband is 4 GHz, and Pattern 3 is configured in the case that thefrequency band is 40 GHz. PTRS may be configured for each frequency bandas in an example where Pattern 5 is configured in the case that thefrequency band is 4 GHz, and Pattern 2 is configured in the case thatthe frequency band is 40 GHz. With the number of resource elements towhich PTRS are mapped being increased for a high frequency bandsusceptible to phase rotation as described above, phase trackingperformance can be improved. With the number of resource elements towhich PTRS are mapped being reduced for a low frequency band regarded asbeing relatively less susceptible to phase rotation as described above,overhead due to PTRS can be reduced. Note that, PTRS may not be mappedin some of low frequency bands unaffected by phase rotation.

In a case that the PTRS pattern is configured, the terminal apparatus 1may increase the number of PTRS in the frequency direction depending ona scheduling bandwidth. For example, in a case that PTRS is mapped ontothe fifth subcarrier in a single resource block, the number ofsubcarriers including PTRS on a frequency axis may be increased inproportion to the number of resource blocks allocated based onscheduling, that is, Downlink Control Information (DCI) transmitted in aphysical downlink control channel. The number of subcarriers includingPTRS on the frequency axis in a resource block may be determined basedon a frequency band. The density of the PTRS in the frequency directionmay be configured, activated, or indicated by RRC, MAC CE, or DCI. Thedensity of the PTRS on the frequency axis may be defined by the numberof resource elements including PTRS in a resource block or the number ofsubcarriers.

Furthermore, the density of the PTRS in the time direction may bedetermined by the frequency band. For example, in a case that thefrequency band is 4 GHz, PTRS may be transmitted based on Pattern 7, andin a case of 30 GHz, the PTRS may be transmitted with Pattern 1. Forexample, in the case that the frequency band is 4 GHz, PTRS may betransmitted based on Pattern 9, and in case 30 GHz, the PTRS may betransmitted with Pattern 6. The density of the PTRS in the timedirection may be configured, activated, or indicated by RRC, MAC CE, orDCI. The density on the time axis may be defined by the number ofresource elements including PTRS in a resource block, the number of OFDMsymbols in a slot, or the number of OFDM symbols in a subframe.

PTRS may be generated differently depending on a Modulation and CodingScheme (MSC) and a modulation scheme. The number of resource elements towhich the PTRS are mapped may be large in a case that the modulationorder is high, and may be small in a case that the modulation order islow. PTRS may be configured for each modulation scheme as in an examplewhere Pattern 3 is configured in a case that a modulation scheme is 256QAM and Pattern 1 is configured in a case that a modulation scheme is 16QAM. PTRS may be configured for each modulation scheme as in an examplewhere Pattern 1 is configured in the case that the modulation scheme is256 QAM and Pattern 4 is configured in a case that the modulation schemeis 16 QAM. With the number of resource elements to which PTRS are mappedbeing increased for a high modulation order as described above, phasetracking performance can be improved. With the number of PTRS beingreduced for a low modulation order, overhead due to PTRS can be reducedwhile maintaining the phase tracking performance. Note that PTRS may notbe mapped in a case that the modulation order is low and the influenceof phase rotation is not considered to be a problem.

PTRS may be configured for each radio transmission scheme. The number ofresource elements to which PTRS are mapped may be configured to be thesame or different between a case that the radio transmission scheme isDFTS-OFDM and a case that the radio transmission scheme is CP-OFDM. Forexample, the same pattern may be selected for the case of DFTS-OFDM andthe case of CP-OFDM. Pattern 1 may be configured in the case ofDFTS-OFDM and Pattern 10 may be configured for the case of CP-OFDM.Thus, different patterns with the same number of PTRS may be configured.With the number of the resource elements to which PTRS are mapped beingthe same between the case of DFTS-OFDM and the case of CP-OFDM asdescribed above, the processing load for generating PTRS can beequalized. Furthermore, the number of PTRS in the case of DFTS-OFDM maybe configured to be greater than the number of PTRS in the case ofCP-OFDM. For example, Pattern 2 may be configured in the case ofDFTS-OFDM and Pattern 1 may be configured in the case of CP-OFDM.Alternatively, Pattern 1 may be configured in the case of DFTS-OFDM, andPattern 4 may be configured in the case of CP-OFDM. With the number ofthe resource elements to which PTRS are mapped being different betweenthe case of DFTS-OFDM and the case of CP-OFDM as described above, phasetracking can be configured to be suitable for characteristics of atransmission scheme.

In the case of DFTS-OFDM, a PTRS symbol may be inserted at a particulartime position before input to DFT. For example, in a case that thenumber of PRBs that are mapped to resource elements by usingfrequency-first mapping for scheduling is 4 (=60 modulation symbols),the PTRS may be inserted into the 6th, 18th (=12+6), 30th (12*2+6), and42th (12*3+6) symbol of the time symbols to be input to DFT forgenerating DFTS-OFDM symbols before DFT spreading. In addition, in acase of mapping to a resource element by using time first mapping, thePTRS may be inserted into the first X symbol(s) before the DFTspreading. The PTRS may be inserted into the X symbol(s) in particularDFTS-OFDM symbols in the slot before the DFT spreading. X may be thenumber of DFTS-OFDM symbols included in the slot. Alternatively, PTRSsymbols may be mapped in a specific pattern prior to DFT. Alternatively,after the DFT spreading PTRS may be mapped in a time and/or at afrequency.

PTRS may be configured in consideration of the moving speed of theterminal apparatus. In a case that the moving speed is high, the numberof resource elements to which the PTRS are mapped may be increased, andin a case that the moving speed is low, the number of resource elementsto which the PTRS are mapped may be reduced. PTRS may be configured inconsideration of the moving speed, as in an example where the pattern 3is configured in the case that the moving speed is high, and the pattern7 is configured in the case that the moving speed is low. PTRS may beconfigured in consideration of the moving speed, as in an example wherethe pattern 3 is configured in the case that the moving speed is high,and the pattern 1 is configured in the case that the moving speed islow. PTRS may be configured in consideration of the moving speed, as inan example where the pattern 2 is configured in the case that the movingspeed is high, and the pattern 8 is configured in the case that themoving speed is low. Accordingly, phase tracking can be performedappropriately in consideration of the moving speed.

Note that PTRS may be configured by using a plurality of conditions. Theplurality of conditions means parameters such as a frequency band, ascheduling bandwidth, an MCS, a modulation scheme, a radio transmissionscheme, and/or a moving speed of the terminal apparatus, and at leastone of the parameters may be selected. For example, PTRS may beconfigured based on a radio transmission scheme and a frequency band, ormay be configured based on a radio transmission scheme, a frequencyband, and a modulation scheme. Note that a pattern of PTRS may bedefined for each radio transmission scheme. For example, in the case ofDFTS-OFDM, the pattern of PTRS may be defined to be Pattern 1, Pattern2, or Pattern 3, and in the case of CP-OFDM, the pattern of PTRS may bedefined to be Pattern 4, Pattern 5, or Pattern 6. Furthermore, in a casethat transmission is performed in a DFTS-OFDM scheme in the frequencyband of 40 GHz, PTRS may be selected from Pattern 1, Pattern 2, andPattern 3, based on the frequency band. Additionally, in the case ofDFTS-OFDM, a pattern where PTRS are mapped at the frequency position ofthe third subcarrier from the bottom may be defined (e.g., Pattern 1,Pattern 4, and Pattern 6). In the case of CP-OFDM, a pattern where thePTRS are mapped at the frequency position of the fifth subcarrier fromthe bottom may be defined.

Note that the base station apparatus 3 and the terminal apparatus 1 mayretain the pattern of PTRS and the pattern number in advance.Furthermore, the base station apparatus 3 may transmit the PTRS patternnumber as reference signal pattern information to the terminal apparatus1. The terminal apparatus 1 may generate PTRS by using the PTRS patternretained in advance and the reference signal pattern informationnotified from the base station apparatus 3. Here, the reference signalpattern information is information for indicating the pattern number ofpredefined PTRS.

The base station apparatus 3 may transmit reference signal mappinginformation to the terminal apparatus 1. Here, the reference signalmapping information is information for indicating a position at whichthe PTRS is mapped. For example, the reference signal mappinginformation may be a subcarrier spacing (e.g., continuation, an intervalwith one subcarrier, or an interval with two subcarriers) for the PTRSmapping, the number of subcarrier onto which the PTRS is mapped, asymbol interval (e.g., continuation, an interval with one symbol, or aninterval with two symbols) at which the PTRS is mapped in the timedirection, a position of the symbol at which PTRS is mapped in the timedirection, or a combination of these. For example, the reference signalmapping information, in which the subcarrier number 3 is configured asinformation of the frequency direction and the continuation isconfigured as information of the time direction, indicates Pattern 1 inFIGS. 6A to 6I. In this case, the base station apparatus 3 notifies theterminal apparatus 1 of the information of the frequency direction andthe information of the time direction as the reference signal mappinginformation. Note that, for example, in a case that the information ofthe frequency direction is predetermined, only the information of thetime direction may be notified, or in a case that the information of thetime direction is predetermined, only the information of the frequencydirection may be notified.

FIG. 10 is a diagram illustrating an overview of a flow of firstprocessing between the base station apparatus 3 and the terminalapparatus 1 according to the present embodiment. In FIG. 10, the basestation apparatus 3 determines the mapping of PTRS and the presence orabsence of PTRS, and indicates the mapping of PTRS and the presence orabsence of PTRS to the terminal apparatus 1. Here, processing involvedin the generation of PTRS will be mainly described.

In S101, the terminal apparatus 1 performs uplink transmission. In thisprocess, the terminal apparatus 1 may transmit UE Capability (terminalcapability information) including phase tracking capability informationto the base station apparatus 3. The phase tracking capabilityinformation is information for indicating whether the terminal apparatus1 has the capability of transmitting PTRS. For example, the phasetracking capability information may be information for indicatingwhether the terminal apparatus 1 has the function of mapping PTRS, ormay be information for indicating whether the terminal apparatus 1 has afunction to support NR. The terminal apparatus 1 may determine whetherto remove phase noise, and determine the phase tracking capabilityinformation in consideration of the result. For example, in a case thatthe terminal apparatus 1 is moving at high speed, the phase trackingcapability information is configured to indicate that the terminalapparatus 1 has the capability of mapping PTRS, for the terminalapparatus 1 to remove phase noise.

In S102, the base station apparatus 3 may configure phase trackingindication information, and may include the phase tracking indicationinformation in DCI. Here, the phase tracking indication information isinformation for indicating whether or not the base station apparatus 3transmits PTRS to the terminal apparatus 1. Note that the base stationapparatus 3 may configure the phase tracking indication informationbased on the phase tracking capability information notified from theterminal apparatus 1. For example, the phase tracking indicationinformation may be configured such that PTRS is transmitted only in acase that the phase tracking capability information indicates that thefunction of mapping PTRS is supported.

In S103, the base station apparatus 3 configures reference signalmapping information or reference signal pattern information. The basestation apparatus 3 may include the reference signal mapping informationor the reference signal pattern information in DCI.

In S104, the base station apparatus 3 performs downlink transmission. Inthis process, the information configured in S102 and S103 is transmittedto the terminal apparatus 1.

In S105, the terminal apparatus 1 interprets the phase trackingindication information. In a case that the phase tracking indicationinformation is configured to indicate to the terminal apparatus 1 totransmit PTRS, the terminal apparatus 1 maps the PTRS to a resourceelement in S106. On the other hand, in a case that the phase trackingindication information is not configured to indicate to the terminalapparatus 1 to transmit PTRS, the terminal apparatus 1 maps no PTRS tothe resource element.

In S106, the terminal apparatus 1 generates PTRS based on theinformation included in DCI and the like, and maps the PTRS to theresource element. In addition to the information included in the DCI,information held by the terminal apparatus may be used. For example, atleast one of the reference signal mapping information or referencesignal pattern information, MCS, a modulation scheme, a frequency band,a radio transmission scheme, information of the moving speed of theterminal apparatus 1 and/or the number of resource blocks allocated tothe terminal apparatus 1, or the like may be used.

In S107, the terminal apparatus 1 performs uplink transmission.

FIG. 11 is a diagram illustrating an overview of a flow of secondprocessing between the base station apparatus 3 and the terminalapparatus 1 according to the present embodiment. In FIG. 11, the basestation apparatus 3 indicates only the presence or absence of PTRS tothe terminal apparatus 1. The base station apparatus 3 and the terminalapparatus 1 have a PTRS configuration rule configured in advance, andbased on the information held, the terminal apparatus 1 generates PTRSand maps the PTRS to a resource element. Note that some reference signsin FIG. 11 are the same as those in FIG. 10, and the processing for thesame reference sign is the same between FIG. 11 and FIG. 10. Points thatare different from FIG. 10 will be mainly described below.

In S201, the terminal apparatus 1 interprets the phase trackingindication information. In S202, in a case that the phase trackingindication information is configured to indicate to the terminalapparatus 1 to transmit PTRS, the terminal apparatus 1 maps the PTRS toa resource element. On the other hand, in a case that the phase trackingindication information is not configured to indicate to the terminalapparatus 1 to transmit PTRS, the terminal apparatus 1 maps no PTRS tothe resource element.

In S202, based on the configuration rule configured in advance, theterminal apparatus 1 generates PTRS and maps the PTRS to a resourceelement. The configuration rule may be determined based on informationincluded in DCI or the like, or may be determined based on informationheld by the terminal apparatus 1. For example, at least one of MCS, amodulation scheme, a frequency band, a radio transmission scheme,information of the moving speed of the terminal apparatus 1 and/or thenumber of resource blocks allocated to the terminal apparatus 1, or thelike may be used.

FIG. 12 is a diagram schematically illustrating a flow of thirdprocessing between the base station apparatus 3 and the terminalapparatus 1 according to the present embodiment. In FIG. 12, the basestation apparatus 3 does not perform an indication of the presence orabsence of PTRS. The base station apparatus 3 and the terminal apparatus1 have a PTRS configuration rule determined in advance, and based on theinformation held, the terminal apparatus 1 generates PTRS and maps thePTRS to a resource element. Note that some reference signs in FIG. 12are the same as those in FIG. 10 or FIG. 11, and the processing for thesame reference sign is the same between FIG. 12 and FIG. 10 or FIG. 11.Points that are different from FIG. 10 and FIG. 11 will be mainlydescribed below.

In S301, the base station apparatus 3 performs downlink transmission. Inthis process, no phase tracking indication information is transmitted.Note that the reference signal mapping information or the referencesignal pattern information may or may not be transmitted.

In S302, based on the configuration rule configured in advance, theterminal apparatus 1 generates PTRS and maps the PTRS to a resourceelement. The configuration rule may be determined based on informationincluded in DCI or the like, or may be determined based on informationheld by the terminal apparatus 1. For example, at least one of MCS, amodulation scheme, a frequency band, a radio transmission scheme,information of the moving speed of the terminal apparatus 1 and/or thenumber of resource blocks allocated to the terminal apparatus 1, or thelike may be used. Note that the configuration rule may include acondition not to generate PTRS. For example, PTRS may not be generatedin a case that the influence of the phase rotation would not cause aproblem. For example, in a case that the reference signal patterninformation is transmitted from the base station apparatus 3, it may bedetermined that a phase tracking indication is present, and the PTRSindicated by the reference signal pattern information may be generated.

Note that in FIG. 10, FIG. 11, and FIG. 12, in the terminal apparatus 1,an antenna port for transmitting PTRS is the same as at least one ofantenna ports for DMRS. For example, in a case that the number ofantenna ports for DMRS is two and the number of antenna ports for PTRSis one, the antenna port for the PTRS may be the same as one or both ofthe antenna ports for the DMRS. The antenna port for the DMRS and theantenna port for the PTRS may be assumed to be quasi co-located (QCL).For example, a frequency offset due to DMRS phase noise is inferred fromthe frequency offset compensated by PTRS. Furthermore, regardless ofwhether PTRS is mapped, DMRS may always be transmitted.

Note that the radio transmission scheme may be configured, activated orindicated by RRC, MAC, and DCI. Thus, the terminal apparatus 1 may mapPTRS in consideration of the radio transmission scheme notified from thebase station apparatus 3.

One aspect of the present embodiment may be operated in carrieraggregation or dual connectivity with Radio Access Technology (RAT),such as LTE and LTE-A/LTE-A Pro. This may be used in some or all ofcells or cell groups, or some or all carriers or carrier groups (such asprimary cell (PCell), secondary cell (SCell), primary secondary cells(PSCell), Master Cell Group (MCG), Secondary Cell Group (SCG), forexample). Moreover, it may be used in a stand-alone application where astand-alone operation is performed.

Configurations of apparatuses according to the present embodiment willbe described below. Here, an example is described where CP-OFDM isapplied as a downlink radio transmission scheme and CP-OFDM, DFTS-OFDM(SC-FDM) is applied as an uplink radio transmission scheme.

FIG. 8 is a schematic block diagram illustrating a configuration of theterminal apparatus 1 according to the present embodiment. As illustratedin FIG. 8, the terminal apparatus 1 is configured to include a higherlayer processing unit 101, a control unit 103, a reception unit 105, atransmission unit 107, and a transmit and/or receive antenna 109.Furthermore, the higher layer processing unit 101 is configured toinclude a radio resource control unit 1011, a scheduling informationinterpretation unit 1013, and a Channel State Information (CSI) reportcontrol unit 1015. Furthermore, the reception unit 105 is configured toinclude a decoding unit 1051, a demodulation unit 1053, a demultiplexingunit 1055, a radio reception unit 1057, and a measurement unit 1059. Thetransmission unit 107 is configured to include a coding unit 1071, amodulation unit 1073, a multiplexing unit 1075, a radio transmissionunit 1077, and an uplink reference signal generation unit 1079.

The higher layer processing unit 101 outputs the uplink data (thetransport block) generated by a user operation or the like, to thetransmission unit 107. The higher layer processing unit 101 performsprocessing of a Medium Access Control (MAC) layer, a Packet DataConvergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, anda Radio Resource Control (RRC) layer.

The radio resource control unit 1011 included in the higher layerprocessing unit 101 manages various pieces of configuration informationof the terminal apparatus 1 itself. Furthermore, the radio resourcecontrol unit 1011 generates information to be mapped to each uplinkchannel, and outputs the generated information to the transmission unit107.

The scheduling information interpretation unit 1013 included in thehigher layer processing unit 101 interprets the DCI (schedulinginformation) received through the reception unit 105, generates controlinformation for control of the reception unit 105 and the transmissionunit 107, in accordance with a result of interpreting the DCI, andoutputs the generated control information to the control unit 103.

The CSI report control unit 1015 indicates to the measurement unit 1059to derive Channel State Information (RI/PMI/CQI/CRI) relating to the CSIreference resource. The CSI report control unit 1015 indicates to thetransmission unit 107 to transmit RI/PMI/CQI/CRI. The CSI report controlunit 1015 sets a configuration to be used in a case that the measurementunit 1059 calculates CQI.

In accordance with the control information originating from the higherlayer processing unit 101, the control unit 103 generates a controlsignal for control of the reception unit 105 and the transmission unit107. The control unit 103 outputs the generated control signal to thereception unit 105 and the transmission unit 107 to control thereception unit 105 and the transmission unit 107.

In accordance with the control signal input from the control unit 103,the reception unit 105 demultiplexes, demodulates, and decodes areception signal received from the base station apparatus 3 through thetransmit and/or receive antenna 109, and outputs the resultinginformation to the higher layer processing unit 101.

The radio reception unit 1057 converts (down-converts) a downlink signalreceived through the transmit and/or receive antenna 109 into a signalof an intermediate frequency, removes unnecessary frequency components,controls an amplification level in such a manner as to suitably maintaina signal level, performs orthogonal demodulation on the basis of anin-phase component and an orthogonal component of the received signal,and converts the resulting orthogonally-demodulated analog signal into adigital signal. The radio reception unit 1057 removes a portioncorresponding to a Guard Interval (GI) from the digital signal resultingfrom the conversion, performs Fast Fourier Transform (FFT) on the signalfrom which the Guard Interval has been removed, and extracts a signal inthe frequency domain.

The demultiplexing unit 1055 demultiplexes the extracted signal intodownlink PCCH, PSCH, and the downlink reference signal. Furthermore, thedemultiplexing unit 1055 makes a compensation of channels including PCCHand PSCH from the channel estimate input from the measurement unit 1059.Furthermore, the demultiplexing unit 1055 outputs the downlink referencesignal resulting from the demultiplexing, to the measurement unit 1059.

The demodulation unit 1053 demodulates the downlink PCCH and outputs aresult of the demodulation to the decoding unit 1051. The decoding unit1051 attempts to decode the PCCH. In a case of succeeding in thedecoding, the decoding unit 1051 outputs downlink control informationresulting from the decoding and an RNTI to which the downlink controlinformation corresponds, to the higher layer processing unit 101.

The demodulation unit 1053 demodulates the PSCH in compliance with amodulation scheme notified with the downlink grant, such as QuadraturePhase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), 64QAM, or 256 QAM, and outputs a result of the demodulation to thedecoding unit 1051. The decoding unit 1051 decodes the data inaccordance with information on transmission or an original coding ratenotified with the downlink control information, and outputs, to thehigher layer processing unit 101, the downlink data (the transportblock) resulting from the decoding.

The measurement unit 1059 performs downlink path loss measurement,channel measurement, and/or interference measurement from the downlinkreference signal input from the demultiplexing unit 1055. Themeasurement unit 1059 outputs, to the higher layer processing unit 101,the measurement result and CSI calculated based on the measurementresult. Furthermore, the measurement unit 1059 calculates a downlinkchannel estimate from the downlink reference signal and outputs thecalculated downlink channel estimate to the demultiplexing unit 1055.

The transmission unit 107 generates the uplink reference signal inaccordance with the control signal input from the control unit 103,codes and modulates the uplink data (the transport block) input from thehigher layer processing unit 101, multiplexes PUCCH, PUSCH, and thegenerated uplink reference signal, and transmits a result of themultiplexing to the base station apparatus 3 through the transmit and/orreceive antenna 109.

The coding unit 1071 performs coding on the Uplink Control Informationand the uplink data input from the higher layer processing unit 101. Themodulation unit 1073 modulates the coded bits input from the coding unit1071, in compliance with a modulation scheme such as BPSK, QPSK, 16 QAM,64 QAM, or 256 QAM.

The uplink reference signal generation unit 1079 generates a sequenceacquired according to a rule (formula) prescribed in advance, based on aphysical cell identifier (also referred to as a Physical Cell Identity(PCI), a cell ID, or the like) for identifying the base stationapparatus 3, a bandwidth to which the uplink reference signal is mapped,a cyclic shift notified with the uplink grant, a parameter value forgeneration of a DMRS sequence, and the like.

On the basis of the information used for the scheduling of PUSCH, themultiplexing unit 1075 determines the number of PUSCH layers to bespatial-multiplexed, maps multiple pieces of uplink data to betransmitted on the same PUSCH to multiple layers through Multiple InputMultiple Output Spatial Multiplexing (MIMO SM), and performs precodingon the layers.

In accordance with the control signal input from the control unit 103,the multiplexing unit 1075 performs Discrete Fourier Transform (DFT) onmodulation symbols of PSCH. Furthermore, the multiplexing unit 1075multiplexes PCCH and PSCH signals and the generated uplink referencesignal for each transmit antenna port. To be more specific, themultiplexing unit 1075 maps the PCCH and PSCH signals and the generateduplink reference signal to the resource elements for each transmitantenna port.

The radio transmission unit 1077 performs Inverse Fast Fourier Transform(IFFT) on a signal resulting from the multiplexing, performs modulationin compliance with an SC-FDM scheme, adds the Guard Interval to theSC-FDM-modulated SC-FDM symbol, generates a baseband digital signal,converts the baseband digital signal into an analog signal, generates anin-phase component and an orthogonal component of an intermediatefrequency from the analog signal, removes frequency componentsunnecessary for the intermediate frequency band, converts (up-converts)the signal of the intermediate frequency into a signal of a highfrequency, removes unnecessary frequency components, performs poweramplification, and outputs a final result to the transmit and/or receiveantenna 109 for transmission.

FIG. 9 is a schematic block diagram illustrating a configuration of thebase station apparatus 3 according to the present embodiment. As isillustrated, the base station apparatus 3 is configured to include ahigher layer processing unit 301, a control unit 303, a reception unit305, a transmission unit 307, and a transmit and/or receive antenna 309.The higher layer processing unit 301 is configured to include a radioresource control unit 3011, a scheduling unit 3013, and a CSI reportcontrol unit 3015. The reception unit 305 is configured to include adecoding unit 3051, a demodulation unit 3053, a demultiplexing unit3055, a radio reception unit 3057, and a measurement unit 3059. Thetransmission unit 307 is configured to include a coding unit 3071, amodulation unit 3073, a multiplexing unit 3075, a radio transmissionunit 3077, and a downlink reference signal generation unit 3079.

The higher layer processing unit 301 performs processing of a MediumAccess Control (MAC) layer, a Packet Data Convergence Protocol (PDCP)layer, a Radio Link Control (RLC) layer, and a Radio Resource Control(RRC) layer. Furthermore, the higher layer processing unit 301 generatescontrol information for control of the reception unit 305 and thetransmission unit 307, and outputs the generated control information tothe control unit 303.

The radio resource control unit 3011 included in the higher layerprocessing unit 301 generates, or acquires from a higher node, thedownlink data (the transport block) mapped to the downlink PSCH, systeminformation, the RRC message, the MAC Control Element (CE), and thelike, and outputs a result of the generation or the acquirement to thetransmission unit 307. Furthermore, the radio resource control unit 3011manages various configuration information for each of the terminalapparatuses 1.

The scheduling unit 3013 included in the higher layer processing unit301 determines a frequency and a subframe to which the physical channels(PSCH) are allocated, the coding rate and modulation scheme for thephysical channels (PSCH), the transmit power, and the like, from thereceived CSI and from the channel estimate, channel quality, or the likeinput from the measurement unit 3059. The scheduling unit 3013 generatesthe control information in order to control the reception unit 305 andthe transmission unit 307 in accordance with a result of the scheduling,and outputs the generated information to the control unit 303. Thescheduling unit 3013 generates the information (e.g., the DCI (format))to be used for the scheduling of the physical channels (PSCH), based onthe result of the scheduling.

The CSI report control unit 3015 included in the higher layer processingunit 301 controls a CSI report that is made by the terminal apparatus 1.The CSI report control unit 3015 transmits information that is assumedin order for the terminal apparatus 1 to derive RI/PMI/CQI in the CSIreference resource and that shows various configurations, to theterminal apparatus 1 through the transmission unit 307.

On the basis of the control information originating from the higherlayer processing unit 301, the control unit 303 generates a controlsignal for controlling the reception unit 305 and the transmission unit307. The control unit 303 outputs the generated control signal to thereception unit 305 and the transmission unit 307 to control thereception unit 305 and the transmission unit 307.

In accordance with the control signal input from the control unit 303,the reception unit 305 demultiplexes, demodulates, and decodes thereception signal received from the terminal apparatus 1 through thetransmit and/or receive antenna 309, and outputs information resultingfrom the decoding to the higher layer processing unit 301. The radioreception unit 3057 converts (down-converts) an uplink signal receivedthrough the transmit and/or receive antenna 309 into a signal of anintermediate frequency, removes unnecessary frequency components,controls the amplification level in such a manner as to suitablymaintain a signal level, performs orthogonal demodulation based on anin-phase component and an orthogonal component of the received signal,and converts the resulting orthogonally-demodulated analog signal into adigital signal.

The radio reception unit 3057 removes a portion corresponding to theGuard Interval (GI) from the digital signal resulting from theconversion. The radio reception unit 3057 performs Fast FourierTransform (FFT) on the signal from which the Guard Interval has beenremoved, extracts a signal in the frequency domain, and outputs theresulting signal to the demultiplexing unit 3055.

The demultiplexing unit 1055 demultiplexes the signal input from theradio reception unit 3057 into PCCH, PSCH, and the signal such as theuplink reference signal. The demultiplexing is performed based on radioresource allocation information that is determined in advance by thebase station apparatus 3 using the radio resource control unit 3011 andthat is included in the uplink grant notified to each of the terminalapparatuses 1. Furthermore, the demultiplexing unit 3055 makes acompensation of channels including PCCH and PSCH from the channelestimate input from the measurement unit 3059. Furthermore, thedemultiplexing unit 3055 outputs an uplink reference signal resultingfrom the demultiplexing, to the measurement unit 3059.

The demodulation unit 3053 performs Inverse Discrete Fourier Transform(IDFT) on PSCH, acquires modulation symbols, and performs receptionsignal demodulation, that is, demodulates each of the modulation symbolson PCCH and PSCH, in compliance with the modulation scheme prescribed inadvance, such as Binary Phase Shift Keying (BPSK), QPSK, 16 QAM, 64 QAM,or 256 QAM, or in compliance with the modulation scheme that the basestation apparatus 3 itself notifies in advance each of the terminalapparatuses 1 with the uplink grant. The demodulation unit 3053demultiplexes the modulation symbols of multiple pieces of uplink datatransmitted on the same PSCH with the MIMO SM, based on the number ofspatial-multiplexed sequences notified in advance with the uplink grantto each of the terminal apparatuses 1 and information designating theprecoding to be performed on the sequences.

The decoding unit 3051 decodes the coded bits of PCCH and PSCH, whichhave been demodulated, at the coding rate in compliance with a codingscheme prescribed in advance, the transmission or an original codingrate being prescribed in advance or being notified in advance with theuplink grant to the terminal apparatus 1 by the base station apparatus 3itself, and outputs the decoded uplink data and uplink controlinformation to the higher layer processing unit 101. In a case that thePSCH is re-transmitted, the decoding unit 3051 performs the decodingwith the coded bits input from the higher layer processing unit 301 andretained in an HARQ buffer, and the demodulated coded bits. Themeasurement unit 309 measures the channel estimate, the channel quality,and the like, based on the uplink reference signal input from thedemultiplexing unit 3055, and outputs a result of the measurement to thedemultiplexing unit 3055 and the higher layer processing unit 301.

The transmission unit 307 generates the downlink reference signal inaccordance with the control signal input from the control unit 303,codes and modulates the Downlink Control Information, and the downlinkdata that are input from the higher layer processing unit 301,multiplexes PCCH, PSCH, and the downlink reference signal, and transmitsa result of the multiplexing or transmits these using differentresources to the terminal apparatus 1 through the transmit and/orreceive antenna 309.

The coding unit 3071 performs coding on the Downlink Control Informationand the downlink data input from the higher layer processing unit 301.The modulation unit 3073 modulates the coded bits input from the codingunit 3071, in compliance with the modulation scheme such as BPSK, QPSK,16 QAM, 64 QAM, or 256 QAM.

The downlink reference signal generation unit 3079 generates, as thedownlink reference signal, a sequence that is already known to theterminal apparatus 1 and that is acquired in accordance with a ruleprescribed in advance based on the physical cell identity (PCI) foridentifying the base station apparatus 3, or the like.

The multiplexing unit 3075, in accordance with the number of PSCH layersto be spatial-multiplexed, maps one or multiple pieces of downlink datato be transmitted on one PSCH to one or multiple layers, and performsprecoding on the one or multiple layers. The multiplexing unit 375multiplexes the downlink physical channel signal and the downlinkreference signal for each transmit antenna port. Furthermore, themultiplexing unit 375 allocates the downlink physical channel signal andthe downlink reference signal to the resource element for each transmitantenna port.

The radio transmission unit 3077 performs Inverse Fast Fourier Transform(IFFT) on the modulation symbol resulting from the multiplexing or thelike, performs the modulation in compliance with an OFDM scheme togenerate an OFDM symbol, adds the Guard Interval to the OFDM-modulatedOFDM symbol, generates a digital signal in a baseband, converts thedigital signal in the baseband into an analog signal, generates anin-phase component and an orthogonal component of an intermediatefrequency from the analog signal, removes frequency componentsunnecessary for the intermediate frequency band, converts (up-converts)the signal of the intermediate frequency into a signal of a highfrequency signal, removes unnecessary frequency components, performspower amplification, and outputs a final result to the transmit and/orreceive antenna 309 for transmission.

(1) More specifically, a terminal apparatus 1 according to a firstaspect of the present invention is configured to communicate with a basestation apparatus and includes a transmission unit configured totransmit Phase-tracking reference signals (PTRS), and an higher layerprocessing unit configured to configure information for indicating atime density and/or a frequency density of the PTRS. A PTRS pattern isconfigured such that the time density of the PTRS is higher for a largerModulation and Coding Scheme (MCS) scheduled for the terminal apparatus,and the frequency density of the PTRS is based on the number of resourceblocks scheduled for the terminal apparatus.

(2) In the first aspect described above, the PTRS are not generated inaccordance with a rule based on the MCS and/or the number of resourceblocks scheduled for the terminal apparatus.

(3) In the first aspect described above, the PTRS are selected from aplurality of the PTRS patterns defined in advance.

(4) In the first aspect described above, information for indicating thetime density and/or the frequency density of the PTRS includesinformation for indicating the PTRS pattern.

(5) In the first aspect described above, the transmission unit transmitscapability information for indicating whether a capability oftransmitting PTRS signals is supported.

(6) A base station apparatus 3 according to a second aspect of thepresent invention is a base station apparatus configured to communicatewith a terminal apparatus, the base station apparatus including: areception unit configured to receive PTRS (Phase-tracking referencesignals); and a higher layer processing unit configured to configureinformation for indicating a time density and a frequency density of thePTRS, in the terminal apparatus, wherein the terminal apparatus uses thetime density of the PTRS which is higher for a larger Modulation andCoding Scheme (MCS) scheduled for the terminal apparatus, and thefrequency density of the PTRS which is based on the number of scheduledresource blocks scheduled for the terminal apparatus.

(A1) More specifically, a terminal apparatus 1 according to an aspect A1of the present invention is a terminal apparatus configured tocommunicate with a base station apparatus, and includes a transmissionunit configured to transmit a first reference signal, a second referencesignal, and a physical uplink shared channel, and a reception unitconfigured to receive first information and a physical downlink controlchannel. The physical uplink shared channel is transmitted based ondownlink control information received using the physical downlinkcontrol channel. The first reference signal is always provided to someof resource elements in a resource block determined based on thedownlink control information. The first information is information withwhich the base station apparatus indicates whether or not to transmitthe second reference signal. Whether the second reference signal ismapped to a resource element is determined based on the firstinformation. The number of resource elements to which the secondreference signal is provided is determined based on the number ofallocated resource blocks determined based on the downlink controlinformation.

(A2) In the aspect A1 described above, the transmission unit furthertransmits second information, and the second information is informationfor indicating whether a capability of transmitting a reference signalfor the phase tracking is supported.

(A3) In the aspect A1 described above, the second reference signal isselected from a plurality of patterns defined in advance.

(A4) In the aspect A1 aspect described above, the second referencesignal is configured in each of a time direction and a frequencydirection.

(A5) In the aspect A1 described above, the downlink control informationincludes information for indicating a pattern of the second referencesignal.

(A6) A base station apparatus 3 according to an aspect A2 of the presentinvention is a base station apparatus configured to communicate with aterminal apparatus, and includes a transmission unit configured totransmit first information using a physical downlink control channel,and a reception unit configured to receive a first reference signal, asecond reference signal and a physical uplink shared channel. The firstreference signal is always provided to some of resource elements in aresource block determined based on the downlink control information. Thefirst information is information with which the base station apparatusindicates whether or not to transmit the second reference signal to theterminal apparatus. Whether the second reference signal is mapped to aresource element is determined based on the first information. Thenumber of resource elements to which the second reference signal isprovided is determined based on the number of allocated resource blocksdetermined based on the downlink control information.

A program running on an apparatus according to an aspect of the presentinvention may serve as a program that controls a Central Processing Unit(CPU) and the like to cause a computer to operate in such a manner as torealize the functions of the above-described embodiment according to thepresent invention. Programs or the information handled by the programsare temporarily stored in a volatile memory such as a Random AccessMemory (RAM), a non-volatile memory such as a flash memory, a Hard DiskDrive (HDD), or any other storage device system.

Note that a program for realizing functions of an embodiment related toan aspect of the present invention may be recorded in acomputer-readable recording medium. The functions may be realized bycausing a computer system to read the program recorded in the recordingmedium for execution. It is assumed that the “computer system” refers toa computer system built into the apparatuses, and the computer systemincludes an operating system and hardware components such as aperipheral device. Furthermore, the “computer-readable recording medium”may be any of a semiconductor recording medium, an optical recordingmedium, a magnetic recording medium, a medium dynamically retaining aprogram for a short time, or any other computer-readable recordingmedium.

Furthermore, each functional block or various characteristics of theapparatuses used in the above-described embodiment may be implemented orperformed in an electric circuit, for example, an integrated circuit ormultiple integrated circuits. An electric circuit designed to performthe functions described in the present specification may include ageneral-purpose processor, a Digital Signal Processor (DSP), anApplication Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA), or other programmable logic devices, discrete gatesor transistor logic, discrete hardware components, or a combinationthereof. The general-purpose processor may be a microprocessor or may bea processor of known type, a controller, a micro-controller, or a statemachine instead. The above-mentioned electric circuit may be constitutedof a digital circuit or an analog circuit. Furthermore, in a case thatwith advances in semiconductor technology, a circuit integrationtechnology appears that replaces the present integrated circuits, one ormore aspects of the present invention can use a new integrated circuitbased on the technology.

Note that, in the embodiment according to one aspect of the presentinvention, an example has been described in which the present inventionis applied to a communication system including a base station apparatusand a terminal apparatus, but the present invention can also be appliedto a system in which terminals communicate with each other, such asDevice to Device (D2D).

Note that the invention of the present patent application is not limitedto the above-described embodiments. In the embodiment, apparatuses havebeen described as an example, but the invention of the presentapplication is not limited to these apparatuses, and is applicable to aterminal apparatus or a communication apparatus of a fixed-type or astationary-type electronic apparatus installed indoors or outdoors, forexample, an AV apparatus, a kitchen apparatus, a cleaning or washingmachine, an air-conditioning apparatus, office equipment, a vendingmachine, and other household apparatuses.

The embodiments of the present invention have been described in detailabove referring to the drawings, but the specific configuration is notlimited to the embodiments and includes, for example, an amendment to adesign that falls within the scope that does not depart from the gist ofthe present invention. Furthermore, various modifications are possiblewithin the scope of one aspect of the present invention defined byclaims, and embodiments that are made by suitably combining technicalmeans disclosed according to the different embodiments are also includedin the technical scope of the present invention. Furthermore, aconfiguration in which constituent elements, described in the respectiveembodiments and having mutually the same effects, are substituted forone another is also included in the technical scope of the presentinvention.

INDUSTRIAL APPLICABILITY

An aspect of the present invention can be utilized, for example, in acommunication system, communication equipment (for example, a cellularphone apparatus, a base station apparatus, a radio LAN apparatus, or asensor device), an integrated circuit (for example, a communicationchip), or a program.

REFERENCE SIGNS LIST

1 (1A, 1B, 1C) Terminal apparatus

3 Base station apparatus

10 TXRU

11 Phase shifter

12 Antenna

101 Higher layer processing unit

103 Control unit

105 Reception unit

107 Transmission unit

109 Antenna

301 Higher layer processing unit

303 Control unit

305 Reception unit

307 Transmission unit

1013 Scheduling information interpretation unit

1015 Channel State Information report control unit

1051 Decoding unit

1053 Decoder unit

1055 Demultiplexing unit

1057 Radio reception unit

1059 Measurement unit

1071 Coding unit

1073 Modulation unit

1075 Multiplexing unit

1077 Radio transmitting unit

1079 Uplink reference signal generation unit

3011 Radio resource control unit

3013 Scheduling unit

3015 Channel State Information report control unit

3051 Decoding unit

3053 Decoder unit

3055 Demultiplexing unit

3057 Radio reception unit

3059 Measurement unit

3071 Coding unit

3073 Modulation unit

3075 Multiplexing unit

3077 Radio transmitting unit

3079 Downlink reference signal generation unit

The invention claimed is:
 1. A terminal apparatus communicating with abase station apparatus, the terminal apparatus comprising: receivingcircuitry configured to receive first information configuring uplinktransmission of a phase tracking reference signal (PTRS), secondinformation configuring time density of the PTRS, third informationconfiguring frequency density of the PTRS, and downlink controlinformation (DCI) including a modulation and coding scheme (MCS) for aphysical uplink shared channel (PUSCH); and transmitting circuitryconfigured to transmit the PUSCH and a demodulation reference signal(DMRS), and further configured to transmit the PTRS based on the firstinformation, the second information and the third information, wherein:the time density of the PTRS configured by the second information isdetermined based on the MCS; the frequency density of the PTRSconfigured by the third information is based on a scheduled resourceelement pattern, the frequency density being proportional to a number ofresource blocks mapped in the pattern for the terminal apparatus totransmit data; the PTRS is not transmitted by the transmitting circuitrybased on the number of resource blocks scheduled for the terminalapparatus to transmit data; and an antenna port used for transmission ofthe PTRS is the same as at least one of antenna ports used fortransmission of the DMRS.
 2. The terminal apparatus according to claim1, wherein the time density of the PTRS is further determined based on afunction of the MCS.
 3. The terminal apparatus according to claim 1,wherein the transmitting circuitry is further configured not to transmitthe PTRS in a case that a predefined rule based on the MCS is satisfied.4. The terminal apparatus according to claim 1, wherein the time densityof the PTRS is set to be higher as the MCS is larger.
 5. A base stationapparatus communicating with one or more terminal apparatuses, the basestation apparatus comprising: transmitting circuitry configured totransmit first information configuring uplink transmission of a phasetracking reference signal (PTRS), second information configuring timedensity of the PTRS, third information configuring frequency density ofthe PTRS, and downlink control information (DCI) including a modulationand coding scheme (MCS) for a physical uplink shared channel (PUSCH);and receiving circuitry configured to receive the PUSCH and ademodulation reference signal (DMRS), and further configured to receivethe PTRS based on the first information, the second information and thethird information, wherein: the time density of the PTRS configured bythe second information is determined based on the MCS; the frequencydensity of the PTRS configured by the third information is based on ascheduled resource element pattern, the frequency density beingproportional to a number of resource blocks mapped in the pattern forthe terminal apparatus to transmit data; the PTRS is not received by thereceiving circuitry based on the number of resource blocks scheduled forthe terminal apparatus to transmit data; and an antenna port used fortransmission of the PTRS is the same as at least one of antenna portsused for transmission of the DMRS.
 6. A method for terminal apparatuscommunicating with a base station apparatus, the method comprising:receiving first information configuring uplink transmission of a phasetracking reference signal (PTRS), second information configuring timedensity of the PTRS, third information configuring frequency density ofthe PTRS, and downlink control information (DCI) including a modulationand coding scheme (MCS) for a physical uplink shared channel (PUSCH);transmitting the PUSCH and a demodulation reference signal (DMRS); andtransmitting the PTRS based on the first information, the secondinformation and the third information, wherein: the time density of thePTRS configured by the second information is determined based on theMCS; the frequency density of the PTRS configured by the thirdinformation is based on a scheduled resource element pattern, thefrequency density being proportional to a number of resource blocksmapped in the pattern for the terminal apparatus to transmit data; thePTRS is not transmitted based on the number of resource blocks scheduledfor the terminal apparatus to transmit data; and an antenna port usedfor transmission of the PTRS is the same as at least one of antennaports used for transmission of the DMRS.
 7. A method for base stationapparatus communicating with one or more terminal apparatuses, themethod comprising: transmitting first information configuring uplinktransmission of a phase tracking reference signal (PTRS), secondinformation configuring time density of the PTRS, third informationconfiguring frequency density of the PTRS, and downlink controlinformation (DCI) including a modulation and coding scheme (MCS) for aphysical uplink shared channel (PUSCH); receiving the PUSCH and ademodulation reference signal (DMRS); and receiving the PTRS based onfirst information, the second information and the third information,wherein: the time density of the PTRS configured by the secondinformation is determined based on the MCS; the frequency density of thePTRS configured by the third information is based on a scheduledresource element pattern, the frequency density being proportional to anumber of resource blocks mapped in the pattern for the terminalapparatus to transmit data; and the PTRS is not received based on thenumber of resource blocks scheduled for the terminal apparatus totransmit data; and an antenna port used for transmission of the PTRS isthe same as at least one of antenna ports used for transmission of theDMRS.
 8. The base station apparatus according to claim 5, wherein thetime density of the PTRS is further determined based on a function ofthe MCS.
 9. The base station apparatus according to claim 5, wherein thetransmitting circuitry is further configured not to transmit the PTRS ina case that a predefined rule based on the MCS is satisfied.
 10. Thebase station apparatus according to claim 5, wherein the time density ofthe PTRS is set to be higher as the MCS is larger.
 11. The methodaccording to claim 6, wherein the time density of the PTRS is furtherdetermined based on a function of the MCS.
 12. The method according toclaim 6, wherein the time density of the PTRS is set to be higher as theMCS is larger.
 13. The method according to claim 7, wherein the timedensity of the PTRS is further determined based on a function of theMCS.
 14. The method according to claim 7, wherein the time density ofthe PTRS is set to be higher as the MCS is larger.